Oxygen Permeable Scleral Contact Lenses Using Patterned Air Cavities

ABSTRACT

A contact lens has a core thick enough to accommodate a payload. The lens further has outer and inner coverings that cover parts of the core. Each covering is a thin layer of gas-permeable material shaped to form a respective cavity between the covering and the core. Oxygen passes through the outer covering to the outer cavity, through an air path within the core to the inner cavity, and through the inner covering to reach the cornea of the wearer&#39;s eye. To increase oxygen flow, a patterned structure is formed at an interface between the core and at least one of the outer and inner covering, comprising supports at which the core and covering contact, and recesses forming the cavity between the core and covering for oxygen flow. Because each recess spans only a short distance between supports, portions of the covering may be made thinner to improve oxygen flow.

BACKGROUND 1. Technical Field

This disclosure relates generally to contact lenses and in particular tooxygen permeable thick contact lenses, for example scleral contactlenses that carry electronic payloads.

2. Description of Related Art

Contact lenses that provide refractive vision correction arecommonplace. Most contact lenses in use today are so-called soft contactlenses. They are relatively thin and made of oxygen permeable hydrogels.Oxygen passes through the contact lens material to the cornea.Sufficient oxygen supply is an important requirement for any contactlens because, due to the lack of blood vessels within the human cornea,the tissue that makes up the cornea receives oxygen through exposure tothe air. Without a sufficient flow of oxygen through the contact lens,the cornea would suffer.

Recently, there has been increased interest in contact lenses thatperform functions other than vision correction. In many of theseapplications, a contact lens may carry a payload for performing variousfunctions. For example, a contact lens may contain a payload of one ormore electrical components, such as projectors, imaging devices,sensors, gyroscopes, batteries, MEMS (micro-electro-mechanical systems),accelerometers and magnetometers, etc. The contact lens must have asufficient thickness and structural integrity to accommodate thepayload. However, increasing the thickness of a contact lens reduces theamount of oxygen that is transmitted through the material of the contactlens to reach the cornea. Often, the payload itself also is not gaspermeable, which further reduces the oxygen flow.

As a result, it can be challenging to provide an oxygenation path fromthe external environment to the cornea, while still meeting the otherrequirements of the contact lens.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure have other advantages and features whichwill be more readily apparent from the following detailed descriptionand the appended claims, when taken in conjunction with the examples inthe accompanying drawings, in which:

FIG. 1A shows a user wearing a display mounted in a scleral contactlens, in accordance with some embodiments.

FIG. 1B shows a cross sectional view of the scleral contact lens displaymounted on the user's eye, in accordance with some embodiments.

FIG. 1C is a functional block diagram of an eye-mounted display using ascleral contact lens.

FIG. 2 is a simplified perspective view of a scleral contacts lens ableto accommodate a thick payload, where the contact lens is configured tobe mounted on the user's eye, in accordance with some embodiments.

FIG. 3A shows a side and a top-down view of a patterned structure formedon the outer covering of a scleral contact lens, in accordance with someembodiments.

FIG. 3B shows views of a first portion of the patterned structure ofFIG. 3A formed on the outer covering of the scleral contact lens.

FIG. 3C shows views of a second portion of the patterned structure ofFIG. 3B formed on the outer covering of the scleral contact lens.

FIG. 4A shows a perspective view of an outer covering of a scleralcontact lens having a substantially uniform thickness, in accordancewith some embodiments.

FIG. 4B shows a perspective view of an outer covering of a scleralcontact lens having a patterned structure formed thereon, in accordancewith some embodiments

FIG. 5A shows a view of a manufactured core component and outer coveringcomponent for a scleral contact lens prior to assembly, in accordancewith some embodiments

FIG. 5B shows side and perspective views of the core component and outercovering component of FIG. 5A assembled together.

FIG. 5C shows side and perspective views of the core component and outercovering component of FIG. 5A assembled together and cut down to formthe scleral contact lens.

FIG. 6A shows a side cross-section view of a core component and outercovering component assembled together, where a patterned structure isformed on the core component, in accordance with some embodiments.

FIG. 6B shows a side cross-section view of the core component and outercovering component of FIG. 6A assembled together and cut down to formthe scleral contact lens.

FIG. 7 is a flowchart of a process for forming a scleral contact lens,in accordance with some embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The figures and the following description relate to preferredembodiments by way of illustration only. It should be noted that fromthe following discussion, alternative embodiments of the structures andmethods disclosed herein will be readily recognized as viablealternatives that may be employed without departing from the principlesof what is claimed.

A contact lens may carry a payload for performing various functions. Forexample, a contact lens may contain a payload of one or more electricalcomponents, such as a projector, an imaging device, one or more sensors,etc. The contact lens must have a sufficient thickness to accommodatethe payload. However, increasing the thickness of a contact lens mayreduce the amount of oxygen that can be transmitted through the materialof the contact lens to reach the cornea.

In order to ensure sufficient corneal oxygenation while maintainingsufficient structural integrity, a scleral contact lens may beconstructed in three layers, including an outer covering, a middlestructure, and an inner covering. The middle structure may contain apayload(s) and is referred to as the core. The core may comprise amaterial having mechanical integrity to carry the payload. In someembodiments, the core material has poor oxygen transmissibility.

A portion of the outward-facing (i.e., facing the external environment)surface of the core is covered by the outer covering in areas that areexposed to ambient oxygen. The inner covering covers an inward-facingsurface of the core above the user's cornea. When worn by a wearer, theouter covering faces the outside environment, while the inner coveringis proximate to the wearer's cornea. The outer covering and innercovering are each a thin layer of gas-permeable material, each shaped toform a respective interstitial cavity between them and the core (alsoreferred to as “air gaps”). The cavities are connected by an air path(e.g., air shafts) that traverses the core. Oxygen from the outsideenvironment passes through the gas-permeable outer covering to reach theouter cavity formed between the outer covering and the core, through theair path to the inner cavity formed between the core and the innercovering, and through the gas-permeable inner covering to reach thecornea of the wearer's eye.

The structure and material of the coverings influences the amount ofoxygen that is able to flow from the outside environment to the user'scornea. The flow of oxygen may be increased by decreasing the thicknessof the coverings. However, thinner coverings do not have the structuralintegrity to span long distances without support. In some embodiments,the inner covering, outer covering, and/or the core are formed to have apatterned structure of varying thicknesses, such as a pattern of blindholes. The patterned structure may be a pattern of recesses interspersedwith supports. The core and covering contact each other at the supports,and the recesses form the cavity for oxygen flow. Because each recessspans only a short distance between supports, the covering may be madethinner, thus increasing oxygen transmission. FIGS. 1-2 below illustratethe general structure of a multi-layer contact lens comprising a core,outer covering, and inner covering, while FIGS. 3-7 illustrateembodiments of patterned structures that may be formed as part of thecontact lens.

FIG. 1A shows a user wearing a display mounted in a scleral contactlens, in accordance with some embodiments. In some embodiments, the usermay wear a scleral contact lens on one eye. In other embodiments, theuser may wear a scleral contact lens over each eye. In cases where theuser wears a pair of scleral contact lens, each of the scleral contactlenses may contain different payloads, allowing each scleral contactlens to perform different functions. For example, in some embodiments,each scleral contact lens may comprise a projector configured to projectimages into a respective eye of the user, but also comprise differentsensors or other components to provide different types of functionality.

In some embodiments, due to space for processing components on thescleral contact lens being limited, the scleral contact lens 100 isconfigured to interface with an external device to provide certainfunctionalities, such as image processing functions, sensor analysisfunctions, etc. In addition, in some embodiments, the scleral contactlens 100 comprises a power coil configured to receive power wirelesslyfrom an external device. In some embodiments, the external device is anaccessary device worn by the user, such as a necklace, headband,glasses, or other wearable device. In other embodiments, the externaldevice is an electronic device such as a mobile phone. In someembodiments, the scleral contact lens 100 may be powered by one or morebatteries within the contact lens, and may interface with an externaldevice for performing certain processing functions. In some embodiments,the external device may be configured to communicate with a remoteserver (e.g., a cloud server).

FIG. 1B shows a cross sectional view of the scleral contact lens mountedon the user's eye, in accordance with some embodiments. Scleral contactlenses are designed to be mounted on the sclera of the user's eye suchthat they do not move around on the wearer's eye when worn. The eye 102includes a cornea 104 and a sclera 106. The scleral contact lens 100 issupported by the sclera 106 and vaults over the cornea 104, typicallyforming a tear fluid layer 108 between the contact lens 100 and thecornea. Oxygen permeates through the contact lens 100 and tear fluidlayer 108 to the cornea 104, at a rate depending upon the geometry ofthe contact lens 100 and the oxygen transmissibility and thicknesses ofthe materials that form the contact lens 100 (not shown in this figure).

The contact lens 100 contains payload(s). These payloads may not begas-permeable and also may require the contact lens to have a thicknessand structural strength sufficient to accommodate and support thepayloads. As a result, the approach used in soft contact lenses forcorneal oxygenation typically will not be adequate for contact lens 100.In some embodiments, the payload(s) may include electronics, includingelectronics that require a power source such as a battery or a coil thatis inductively powered. In the example of FIG. 1B, the payloads includea small projector that projects images onto the wearer's retina(referred to as a femtoprojector 114), and the corresponding electronics112 to operate the femtoprojector. In some embodiments, both of theseare powered by a coil 145 around the periphery of the contact lens. Inother embodiments, the femtoprojector 114 and electronics 112 may bepowered by a battery located within the contact lens 100 (not shown).

The femtoprojector 114 may include an LED frontplane with an LED array,an ASIC backplane with electronics that receives the data to drive theLED frontplane, and optics to project light from the LED array onto theretina. The femtoprojector 114 preferably fits into a 2 mm by 2 mm by 2mm volume or even into a 1 mm by 1 mm by 1 mm volume. The contact lens100 must be sufficiently thick and structurally sound to support thefemtoprojector 114 and electronics 112, while still maintaining adequateoxygen flow to the cornea.

To allow the femtoprojector 114 to project images onto the user'sretina, the femtoprojector 114 may be positioned over the cornea. On theother hand, the electronics 112 may be positioned away from the cornea,as shown in FIG. 1B. For convenience, the contact lens 100 is dividedinto a central zone and a peripheral zone. The central zone may refer toan area of the contact lens that overlaps the cornea 104 of the eye 102,while the area of the contact lens outside the cornea is referred to asthe peripheral zone. As illustrated in FIG. 1B, the femtoprojector 114is located within the central zone of the contact lens, while theelectronics 112 and coil 145 are located in the peripheral zone. Peoplehave eyes of different sizes and shapes. The diameter of the boundarybetween the cornea and the sclera is typically between 10 and 12.5 mm,so for convenience, the central zone may be defined as the 10 mmdiameter center area of the contact lens (i.e., within 5 mm radius ofthe center axis of the contact lens). Payload components that projectlight onto the retina typically will be located within the central zonedue to the required optical path. Conversely, payload components that donot project light onto the retina or otherwise interact with the retinamay be located on the edge of the central zone or outside the centralzone so that they do not block light from reaching the retina.

Other examples of powered payloads include sensors, imagers, and eyetracking components such as accelerometers, gyroscopes andmagnetometers. Payloads may also include passive devices, such as a coilor antenna for wireless power or data transmission, capacitors forenergy storage, and passive optical structures (e.g., absorbing lightbaffles, beam-splitters, imaging optics). The contact lens 100 may alsocontain multiple femtoprojectors, each of which projects images onto theuser's retina. Because the contact lens 100 moves with the user's eye102 as the user's eye rotates in its socket, the femtoprojectors mountedin the contact lens 100 will also move with the user's eye and projectto the same region of the retina. Some femtoprojector(s) may alwaysproject images to the fovea, and other femtoprojector(s) may alwaysproject images to more peripheral regions which have lower resolutions.As a result, different femtoprojectors may have different resolutions.The images from different femtoprojectors may be overlapping, to form acomposite image on the wearer's retina. Contact lens having one or morefemtoprojectors may hereafter referred to as “contact lens displays” or“eye mounted displays.”

FIG. 1C is a functional block diagram of an eye-mounted display using ascleral contact lens, in accordance with some embodiments. The displaycan be divided into a data/control subsystem 150 and a power subsystem170. In some embodiments, the receive path of the data/control subsystem150 includes an antenna 152, receiver circuitry 154, a data pipeline156, and a femtoprojector 160. Data from an external source (e.g., anexternal device such as an accessory device) is wirelessly transmittedto the display via the antenna 152. The receiver circuitry 154 performsthe functions for receiving the data, for example demodulation, noisefiltering, and amplification. It also converts the received signals todigital form. The pipeline 156 processes the digital signals for thefemtoprojector 160. These functions may include decoding, and timing.The processing may also depend on other signals generated internallywithin the contact lens, for example eye tracking 158 or ambient lightsensing. The femtoprojector 160 then projects the corresponding imagesonto the wearer's retina. In this example, the femtoprojector 160includes a CMOS ASIC backplane 162, LED frontplane 164 and optics 166,as described previously.

The data/control subsystem 150 may also include a back channel throughtransmitter circuitry 154 and antenna 152. For example, the contact lensmay transmit eye tracking data, control data and/or data about thestatus of the contact lens.

In some embodiments, power is received wirelessly via a power coil 172.This is coupled to circuitry 174 that conditions and distributes theincoming power (e.g., converting from AC to DC if needed). The powersubsystem 170 may also include energy storage devices, such as batteries176 or capacitors (not shown), in addition to or instead of the powercoil 172. For example, in some embodiments, the power coil 172 is usedto charge the battery 176, which distributes power to the components ofthe data/control subsystem 150. In some embodiments, the contact lensmay comprise the battery 176 but no power coil 172, or vice versa.

In addition to the components shown in FIG. 1C, the overall system mayalso include components that are outside the contact lens (i.e.,off-lens). For example, head tracking and eye tracking functions may beperformed partly or entirely off-lens (e.g., sensor within the contactlens may transmit raw sensor data to an external device, which analyzesthe received data to calculate a head or eye orientation). The datapipeline may also be performed partially or entirely off-lens. Each ofthe arrows on the left-hand side of FIG. 1C also connects to an off-lenscomponent. The power transmitter coil is off-lens, the source of imagedata and control data for the contact lens display is off-lens, and thereceive side of the back channel is off-lens.

There are many ways to implement the different system functions. Someportions of the system may be entirely external to the user, while otherportions may be worn by the user in the form of a headpiece or glasses.Components may also be worn on a belt, armband, wrist piece, necklace,or other types of packs. For example, in some embodiments, the contactlens may receive image content to be displayed by the femtoprojector 160from an external device associated with the user via the antenna 152.The external device may further communicate with a server (e.g., aremote server) to generate the image content.

FIG. 2 is a simplified perspective view of a scleral contacts lens ableto accommodate a thick payload, where the contact lens is configured tobe mounted on the user's eye, in accordance with some embodiments. Insome embodiments, a thick payload may refer to a payload greater than500 um in thickness. With respect to the contact lens, terms such as“outer” “over” “top” and “up” refer to the direction away from thewearer's eye, while “inner” “under” “bottom” and “down” refer to thedirection towards the wearer's eye. The scleral contact lens 200includes a core 210 that carries the payload(s). The core 210 has a basesurface 216 that mounts to the sclera of the eye, an outer surface 212that faces outwards towards the external environment, and an innersurface 213 that faces inwards towards the cornea of the eye. Thecontact lens 200 also includes an outer covering 220 that covers theouter surface 212 of the core, and an inner covering 230 that covers theinner surface 213 of the core. Each covering 220, 230 forms acorresponding air cavity 225, 235 between the covering and the core 210.An air path 240 through the core 210 connects the two cavities 225, 235.

Together, the outer covering 220, core 210, and inner covering 230 forma three-layer contact lens 200. The outer covering 220, core 210, andinner covering 230 are shaped such that when the contact lens isassembled, an outer cavity 225 is formed between the outer covering 220and the core 210, and an inner cavity 235 is formed between the core 210and the inner covering 230. Because the outer and inner cavities 225 and235 are each entirely enclosed by their respective structures, thecavities are not directly exposed to the external environment,preventing any debris or other contaminants from the outside air or fromthe tear layer from potentially reaching either cavity.

The outer covering 220 is exposed to air or separated from air by a thintear layer that forms over the covering. As such, oxygen diffuses fromthe surrounding air through the gas permeable material of the outercovering 220 (and thin tear layer) to reach the outer cavity 225. Theoxygen in the outer cavity 225 diffuses through an air path 240 totraverse through the thickness of the core 210 to reach the inner cavity235. From the inner cavity 235, oxygen diffuses through the gaspermeable material of the inner covering 230 to reach the tear fluidlayer and underlying cornea of the wearer. Because the inner cavity 235may cover all or most of the wearer's cornea, oxygen may be distributedevenly across the wearer's cornea through the inner covering 230. Insome embodiments, one or more surfaces the outer covering and/or theinner covering may be covered with a coating of hydrophilic material, tomake the contact lens more comfortable to wear (e.g., by improvinglubricity of the contact lens) and/or to preserve gas permeability ofthe coverings. In some embodiments, portions of the core not covered bythe outer and inner coverings (such as the exposed portions of the outersurface of the core) are covered with a coating of hydrophilic material,to increase wearer comfort by improving lubricity.

Oxygen diffusion through the air (such as in the cavities 225, 235 andair path 240) is roughly 100,000 times more rapid than diffusion throughpermeable solids such as rigid gas permeable (“RGP”) plastic. As aresult, the oxygen transmissibility of the contact lens 200 is definedprimarily by the thicknesses and materials of the two coverings 220,230, and not by the thickness of the cavities 225, 235, air path 240, orthe core 210. The oxygen transmissibility “Dk/t” of the entire contactlens 200 may be approximated based upon the Dk/t of the areas of theouter covering 220 and inner covering 230 overlapping the outer cavity225 and inner cavity 235, respectively, and not on the thickness ormaterial of the core 210. The thickness and material of the core 210 maybe selected to accommodate a desired payload and provide sufficientstructural strength to support the payload. Here, Dk is oxygenpermeability, where D is a diffusion constant measured in

$\left( \frac{{cm}^{2}}{\sec} \right),$

and k is a concentration of O₂ per unit of O₂ partial pressure and ismeasured in

$\left( \frac{{ml}_{O_{2}}}{ml} \right){\left( \frac{1}{{mmH}g} \right).}$

The t is thickness of the material. Dk/t is often quoted in units of10⁻¹¹

$\left( \frac{{cm}^{2}}{\sec} \right)\left( \frac{{ml}_{O_{2}}}{ml} \right){\left( \frac{1}{{mmH}g} \right).}$

Some sources recommend an oxygen transmissibility of Dk/t=24 as theminimum for daily wear contact lenses, and an oxygen transmissibility ofDk/t=87 as the minimum recommended for extended wear lenses in contactwith the cornea.

In FIG. 2, the inner covering 230 and inner cavity 235 are large enoughto cover substantially all of the cornea. In this way, oxygen candiffuse from the cavity 235 through the inner covering 230 directly toall parts of the cornea. Lateral diffusion through the inner covering230 or tear layer is generally not required. To accommodate typicalcorneas, the inner covering 230 and inner cavity 235 each have acircular edge of at least approximately 10-13 mm in diameter.

For the outer covering 220 and outer cavity 225, the location is lessimportant than the overall surface area exposed to ambient oxygen. Insome designs, the outer structure 220, 225 has a same surface area asthe inner structure 230, 235. That is, in FIG. 2, the overlap areabetween the outer covering 220 and outer cavity 225 is at least equal tothe overlap area between the inner covering 230 and inner cavity 235.

The air path 240 in FIG. 2 is a single air shaft through a solid sectionof the core 210, for example a 1 mm diameter air shaft. Because oxygendiffusion in air is high, the specific shape and location of the airpath 240 is secondary in importance, so long as it connects the twocavities 225, 235. For example, the air path may be implemented as twoor more air shafts instead of one air shaft. It may also be located in aperiphery of the contact lens, for example outside a 10 mm diametercentral zone, so that it does not interfere with light entering the eye.

The coverings 220,230 are each relatively thin in comparison to the core210 and are made of materials that are permeable to oxygen such as rigidgas permeable (“RGP”) plastic. On the other hand, the core 210 issufficiently thick to accommodate the payloads, such as femtoprojectorsand electronic components. The core 210 may also be made from an oxygenpermeable material such as RGP, or from an oxygen impermeable materialsuch as poly(methyl methacrylate) (“PMMA”). The approach described abovemay also be used when the core 210 does not contain a payload, but is sothick that it would have insufficient oxygen transmission. In someembodiments, the outer covering 220, core 210, and inner covering 230are bonded to each other via an adhesive. Suitable adhesives may includeglues such as medical grade optical cement. Example glues that may beappropriate for this application include UV-curable optical adhesivesfrom Henkel Loctite.

In some embodiments, such as in the design shown in FIG. 2, the core210, rather than the inner covering 230, makes contact with the sclerathrough the base surface 216. This provides additional space in the coreto accommodate payloads, compared to designs in which the core does notextend all the way to the sclera. This approach may also provide morepayload space located close to the perimeter of the contact lens. Forexample, a coil may be located closer to the perimeter, resulting in alarger area coil and more efficient power transfer. The core 210material is also a good structural material to support the payloads.

In some embodiments, the outer covering 220 has an annular shape anddoes not cover a center area of the contact lens. Because the outercovering 220 does not extend to the center of the core 210, the outercovering 220 does not contribute to the total thickness at the center ofthe contact lens 200. As a result, the contact lens 200 has a reducedthickness in comparison to a contact lens having an outer covering thatalso covers the center of the core. In addition, if the center hole ofthe outer covering 220 is large enough (e.g., 8 mm diameter or larger),it will not interfere with light passing through the contact lens toreach the wearer's eye, eliminating potential optical reflection orscattering that may occur at the boundaries between the outer covering220, the outer cavity 225, and the core 210. Furthermore, an annularouter covering 220 may be more durable and more easily supported by thecore 210 in comparison to one that must be supported over the entirecenter area of the contact lens. Thus, the outer covering 220 can bemade thinner while still maintaining structural integrity, whichincreases the oxygen transmission through the outer covering.

In addition, both coverings 220, 230 are flush with the core 210. Theouter surface 212 of the core has a recess for the outer covering 220,so that the outer covering and the core's adjoining outer surface 212form a smooth surface. Because the eyelid blinks over the contact lens,a smooth outer surface is more comfortable, as well as providing anoverall thinner contact lens as described above. The inner surface 213of the core also has a recess for the inner covering 230, also resultingin a smooth surface between the two.

While the outer covering 220 is illustrated in FIG. 2 as a singleannular piece, in some embodiments, the outer covering may be composedof several separate pieces. When placed over the core, each of the outercovering pieces forms a separate outer cavity between it and the core,each of which is connected to the inner cavity via a respective airpath. In some embodiments, each of the outer covering pieces may beseparated by a space when placed over the core, while in otherembodiments, the outer covering pieces directly abut each other whenplaced over the core. Using separate pieces for the outer covering canreduce the mechanical stress on each piece.

In some embodiments, the scleral contact lens may be oval in shape. Thecontact lens may have a non-circular perimeter that extends below theupper and lower eyelids when mounted on the user's eye (e.g., an “oval”perimeter that is elongated along the direction of the eye opening). Dueto the curvature of the eye, the actual shape of the perimeter isthree-dimensional. However, for convenience, it will be referred to asoval. Due to the size of the contact lens, it is partially covered bythe user's eyelids. One advantage of a non-circular perimeter is thatthe contact lens may be larger and has more space to carry payloads.Another advantage is that the perimeter is larger so that larger coils(e.g., coil 145) may be used. For example, the coil 145 may comprise aconductive coil constructed so that it lies parallel to and within 0.3mm to 3 mm of the oval perimeter of the contact lens. Although thecontact lens is larger with a non-circular perimeter, in someembodiments, the inner covering and inner cavity may have the samecircular size and shape as described previously since that is sufficientto oxygenate the cornea.

As discussed above, the amount of oxygen that is able to flow from theoutside environment to reach the user's cornea is dependent on thestructure and material of the outer and inner coverings. In someembodiments, in order to facilitate oxygen flow, at least one of theinner covering, the outer covering, and the core is formed to have apatterned structure of varying thicknesses, such as a pattern ofrecesses interspersed with supports. The patterned structure may beformed on an inner surface of the outer covering, on an outer surface ofthe inner covering, on a portion of the outer surface of the core facingthe outer covering, or on a portion of the inner surface of the corefacing the inner covering. For ease of discussion, FIGS. 3 and 4 belowshow the patterned structure as being formed on the inner surface of theouter covering. In such an arrangement, the core and outer coveringcontact each other at the supports of the patterned structure, while therecesses of the patterned structure form the cavity between the core andouter covering, allowing for oxygen flow from the external environmentto pass through the outer covering to the cavity. Because each recessspans only a short distance between supports, the outer covering may bemade thinner without compromising structural integrity.

In some embodiments, the patterned structure comprises a pattern ofblind holes. FIG. 3A shows a side and a top-down view of a patternedstructure formed on the outer covering of a scleral contact lens, inaccordance with some embodiments. As illustrated in FIG. 3A, a patternof blind holes 310 are formed on an inner surface of the outer covering305 of the scleral contact lens. In this example, the maximum thickness320 of the outer covering 305 is 150 um (microns). Each of the blindholes 310 creates a recess within the outer covering 305 where the outercovering has a reduced thickness 315 (15 um in this example). In someembodiments, the reduced thickness 315 of the outer coveringcorresponding to the recesses defined by the blind holes 310 issignificantly smaller than the maximum thickness 320 of the outercovering (e.g., 10% of the maximum thickness). For example, in someembodiments, the outer covering (prior to forming of the patternedstructure) may have a thickness of approximately 150 um, while thethickness of the outer covering within the recesses may be approximately15 um. It is understood that any specific dimensions discussed hereinare used solely for purpose of example, and that patterned structuresand contact lens components may have dimensions other than thosediscussed herein.

The patterned structure is formed such that when the outer covering 305is placed over the core 325, portions of the outer covering 305 betweeneach of the blind holes 310 will contact the outer surface of the core325. As such, each portion of reduced thickness of the outer covering305 (defined by the blind holes 310) spans only a short distance overthe core 325. This allows for the thickness of outer covering 305 withinthe recesses to be reduced, while still maintaining structuralintegrity.

In some embodiments, one or more pillars 330 are formed on the portionsof the outer covering 305 between the blind holes 310. When the outercovering 305 is placed over the core 325, the pillars 330 function tosupport the outer covering 305 on the core 325, as well as space aportion of outer covering 305 between the blind holes 310 away from thecore 325. This space between the pillars 330 defines the air cavity 335connecting adjacent blind holes 310 and allowing air to flow betweenthem. The blind holes 310 and their connecting channels 335 thuscollectively form a single cavity between the outer covering 305 and thecore 325, allowing oxygen passing through the outer covering 305 at thelocation of any of the blind holes 310 to reach an air passage(s) withinthe core (e.g., air path 240) and the inner cavity.

In some embodiments, the blind holes 310 are formed in a hexagonalpattern, where each of the blind holes 310 is surrounded by six adjacentblind holes. In addition, as illustrated in FIG. 3A, each pillar 330 maybe located between three adjacent blind holes 310. In other embodiments,the blind holes 310 may be formed in a rectangular pattern or other typeof pattern. In some embodiments, the blind hole pattern of the patternedstructure is configured such that a distance between pillars 330 in thepatterned structure does not exceed 1 mm.

In some embodiments, the blind hole pattern illustrated in FIG. 3A isformed using a plurality of overlaid blind hole patterns, e.g., a firstblind hole pattern comprising blind holes of a first radius and a firstdepth, and a second blind hole pattern comprising blind holes of asecond radius and a second depth. In some embodiments, the first andsecond blind hole patterns are aligned, such that the blind holes of thefirst and second blind hole patterns share central axes. As such, thespacing of the blind holes of the first blind hole pattern is the sameas the spacing of the blind holes of the second blind hole pattern.

Examples of the use of first and second overlaid blind hole patterns tocreate the overall pattern are discussed in relation to FIGS. 3B and 3Cbelow. FIG. 3B shows views of a first step in forming the patternedstructure of FIG. 3A. In this first step, large overlapping blind holes340 of shallow depth are cut into the outer covering, thus creating thepillars 330. The depth corresponds to a desired height of the pillars330. Because oxygen diffusion through the air (e.g., within the channels335 formed between the pillars 330) is roughly 100,000 times more rapidthan diffusion through permeable solids (such as that used to form theouter covering 305), the height of each pillar 330 (and the height ofthe resulting channels 335 formed between them) may be small compared tothe total thickness of the outer covering 305 (e.g., between 5-10% ofthe thickness of the outer covering). This allows for the pillars 330 tomore stably support the outer covering 305 on the core 325, while thechannels 330 will still provide sufficient air flow between the blindholes 310.

The radius of these blind holes is selected to be greater than thespacing between the blind holes, such that the blind holes 340 willpartially overlap when formed on the outer covering 305. However, theradius is selected such that material is left between adjacent blindholes to form the pillars 330. For example, in a hexagonal blind holepattern, such as that illustrated in FIG. 3B, each pillar 330 is definedby the material left between three adjacent blind holes 340.Consequently, each blind hole 340 forms six pillars corresponding to thematerial left between it and its six adjacent blind holes. In thisexample, the blind holes cover a 4.5 mm wide swath of the outercovering.

FIG. 3C shows views of a second step in forming the patterned structureof FIG. 3A. Here, a second blind hole 310 pattern is formed on the outercovering 305 after the formation of the first blind hole pattern of FIG.3B. While the first blind hole pattern defines the pillars 330, thesecond blind hole pattern defines the recesses of the outer covering305. In some embodiments, each of the blind holes of the second blindhole pattern is aligned with a central axis of a corresponding blindhole 340 of the first blind hole pattern (e.g., such that the blindhole310 is centered between a set of pillars 330 formed by the first blindhole pattern). The depth of these blind holes 310 is selected based upondesired reduced thickness 315 of the outer covering within the recessedregions of the patterned structure.

Consequently, after both the first and second blind hole patterns havebeen formed on the outer covering 305, the surface of the outer covering305 will comprise a plurality of recesses (e.g., defined by the blindholes 310 of the second blind hole patterns) where the thickness of theouter covering is greatly reduced, positioned between supports havingpillars 330 where the outer covering 305 is supported by the core 325.Because the rate at which air (including oxygen) is able to pass throughthe outer covering is inversely proportional to the thickness of theouter covering, oxygen transmission through the outer covering 305 atthe recesses is greatly increased due to the reduced thickness 315 ofthe outer covering. Oxygen may pass between different blind holes 310via the passages 335 formed by spaces between the pillars 330,connecting the blind holes 310 of the patterned structure tocollectively form a single cavity between the outer covering and core ofthe contact lens. Oxygen can thus pass through the gas permeablematerial of the outer covering from the external environment to therecesses defined by the blind holes, and flow between the blind holes toreach an air passage through the core (e.g., the air path 240illustrated in FIG. 2) to the inner cavity, where it may then passthrough the inner covering to oxygenate the user's cornea.

Although FIGS. 3B and 3C illustrate the second blind hole pattern formedafter the first blind hole pattern, it is understood that in otherembodiments, the first and second blind hole patterns may be formed in adifferent order.

In addition, although FIGS. 3A-3C illustrate the blind holes of thepatterned structure as cylindrical blind holes, it is understood that insome embodiments, the patterned structure may comprise a blind holepattern in which the blind holes are of a different shape. For example,in some embodiments, the patterned structure comprises a blind holepattern in which each blind hole is shaped as a frustum, in which a sizeof the blind hole decreases with depth within the outer covering, i.e.,from a first, larger size at the surface of the outer covering on whichthe blind hole is formed, to a second, smaller size at the maximum depthof the blind hole. In some embodiments, the first and second sizes areselected such that the blind holes will partially overlap up to acertain depth. Material left in non-overlapping regions between adjacentblind holes function as pillars to support the outer covering on thecore, while gaps formed by areas of overlap between adjacent blind holesform passages allowing for air flow between the blind holes of thepattern.

Because the patterned structure allows for portions of the outercovering to be greatly reduced in thickness (e.g., ˜10% compared to anoriginal thickness of the outer covering), an overall surface area ofthe outer covering required to achieve a desired level of oxygentransmission may be reduced, due to oxygen transmissibility beingdirectly proportional to surface area and inversely proportional tothickness of the outer covering.

FIG. 4A shows a perspective view of an outer covering of a scleralcontact lens having a substantially uniform thickness, in accordancewith some embodiments. The outer covering 405, when mounted on the coreof a contact lens, may contact the core only at the edges of the outercovering, and define an outer cavity between an inner surface thereofand an outer surface of the core having a substantially uniformthickness. To maintain a desired level of structural integrity, theouter covering may need to have at least a minimum thickness. Inaddition, to achieve a desired level of oxygen transmission, the outercovering 405 may need to have at least a particular surface area for agiven thickness. For example, in some embodiments, the outer coveringmay have a thickness of 150 um and cover a surface area of 140 mm² onthe core to achieve a desired oxygenation level.

FIG. 4B shows a perspective view of an outer covering of a scleralcontact lens having a patterned structure formed thereon, in accordancewith some embodiments. The patterned structure 415 formed on the outercovering 410 may comprise the overlaid blind hole pattern such as thatillustrated in FIGS. 3A-3C (e.g., first and second overlaid blind holepatterns forming a plurality of blind holes and pillars between adjacentblind holes). The patterned structure 415 of the outer covering 410creates intermittent points of support (e.g., at the pillars 330illustrated in FIGS. 3A-3C) between the outer covering 410 and the corewhen outer covering 410 is assembled on the core. Because the recessedregions of patterned structure 415 formed in the outer covering 410 havereduced thickness, the amount of oxygen transmission of the outercovering 410 for a given surface area may be increased. As an example,if the recesses of the patterned structure cover 50% of the outercovering and are 80% thinner than the thickness of FIG. 4A, then anamount of oxygen transmission for a given surface area may be increasedby at least

${\frac{50\%}{\left( {1 - {80\%}} \right)} - 1} = {150{\%.}}$

As such, a total surface area of the core that is covered by the outercovering may be reduced. For example, the outer covering 410 illustratedin FIG. 4B (having a patterned structure 415 formed thereon) may have areduced surface area in comparison to the outer covering 405 illustratedin FIG. 4A (having substantially uniform thickness), but may still beable to provide a similar amount of oxygen transmission to the outercavity of the contact lens. In some, the outer covering 410 has anannular shape with a width of 3 mm or less. If the patterned structureincreases the oxygen transmission by 150% (i.e., 2.5× the oxygentransmission in FIG. 4A), then the surface area can be 40% of thesurface area in FIG. 4A and still maintain the same oxygen transmission.In some embodiments, the patterned structure is configured such that therecesses of the patterned structure occupy at least a thresholdpercentage (e.g., >50%) of an overall area of the patterned structure,to ensure that the benefit to oxygen transmissibility from having areduced thickness of the outer covering at the recesses offsets thereduction in transmissible surface area due to contact between the innercovering and core at the supports. In some embodiments, the outercovering may be configured to have, within the area of the patternedstructure, an average thickness of less than 100 um, and cover an areaon the contact lens of not more than 100 mm². In some embodiments, thepatterned structure is configured to cover at least a threshold amountof the outer covering (e.g., at least ⅓ of an overall area of the outercovering). Reducing a surface area of the core covered by the outercovering may allow for additional flexibility regarding placement ofvarious components and payloads on the core (e.g., outer covering,payload components such as electronic components, power coils, etc.).

While the above discussion refers primarily to embodiments where thepatterned structure comprises a pattern of blind holes, it is understoodthat the patterned structure may comprise any type of structure thatdefines a plurality of recesses interspersed between a plurality ofsupports. For example, in some embodiments, the patterned structure maycomprise a plurality of grooves formed on the inner surface of the outercovering. Regions of the outer covering between the formed groovesdefine ridges that support the outer covering when placed on the core,while the grooves define recesses where the outer covering is of reducedthickness, facilitating oxygen transmission from the outside environmentinto the grooves. In some embodiments, the plurality of grooves areconnected to each other by one or more passages, allowing for air flowbetween the grooves. For example, in embodiments where the outercovering is annular in form (e.g., as illustrated in FIGS. 2 and 4B),the patterned structure may comprise a plurality of circumferentialgrooves formed on the outer covering, with one or more additionalgrooves oriented orthogonally to the circumferential grooves to formpassages connecting the circumferential grooves.

In some embodiments, the patterned structure is formed on an outersurface of the core instead of an inner surface of the outer covering.For example, the patterned structure may comprise a plurality ofcircumferential grooves formed on an outer surface of the core, whereasthe outer covering may be of substantially uniform thickness. Whenmounted on the core, the ridges between pairs of adjacent grooves on thecore directly contact an inner surface of the outer covering,functioning as supports for the outer covering, while the space betweenthe inner surface of the outer covering and the grooves with the coreform the outer cavity. In some embodiments, the outer covering is formedto be of substantially uniform thickness. However, due to beingperiodically supported by the patterned structure formed on core, thethickness of the outer covering may be reduced compared to an outercovering that is supported only at its edges.

In some embodiments, forming the patterned structure on the outersurface of the core instead of on an inner surface of the outer coveringmay improve oxygen transmissibility. Because the outer covering can beformed to be of a reduced uniform thickness, as the supports which wouldcorrespond to areas of increased thickness of the outer covering areformed on the core instead of on the outer covering, the impact of thesupports on oxygen transmissibility is reduced. In addition, in someembodiments, the supports of the patterned structure formed on core maybe rounded, pointed, or otherwise shaped to reduce a contact area withthe outer covering, increasing an amount of surface area of the outercovering that contributes to oxygen transmission. In some embodiments,the outer covering over the patterned structure formed on the core mayhave an average thickness of not more than 100 um.

Due to the outer covering contacting the core at the supports of thepatterned structure when the outer covering is mounted to the core, theportions of the outer covering having reduced thickness (e.g., recesses)will only span a short distance (e.g., corresponding to a distancebetween supports). However, prior to the outer covering being assembledon the core, these portions of reduced thickness may cause the outercovering to be difficult to handle, due to lack of support from the coreleading to potential folding or breakage of the outer covering.

In some embodiments, instead of forming the core and outer covering totheir final desired thicknesses, the outer covering and/or the core areinitially formed as an outer covering component and/or core componenthaving a larger thickness, which is then cut down to the desiredthickness after assembled together. This may help to ensure that theouter covering is thick enough to handle prior to being mounted on (andthus receiving support from) the core.

FIG. 5A shows an exploded view of a manufactured core component andouter covering component for a scleral contact lens prior to assembly,in accordance with some embodiments. The outer covering component 505 isformed from an oxygen permeable material, and has a thickness thatfacilitates handling of the outer covering component 505. In addition,the core component 510 may also be formed to be thicker than its finaldesired form. For example, in some embodiments, the core component 510may include one or more alignment features or edges 515 that serve toalign the outer covering component 505 when placed over the corecomponent 510, to ensure that the outer covering component 505 ispositioned correctly relative to the core component 510. The corecomponent 510 may further comprise one or more features to facilitatehandling of the core component 510.

A patterned structure comprising a plurality of recesses interspersedbetween a plurality of supports is formed on either the outer coveringcomponent 505 or the core component 510. For example, as illustrated inFIG. 5A, the patterned structure may correspond to a plurality ofcircumferential grooves 520 formed on a portion of the core component510. In addition, an additional groove 525 may be formed as part of thepatterned structure to function as a passage between the grooves of thecircumferential grooves 520.

FIG. 5B shows side and perspective views of the core component and outercovering component of FIG. 5A assembled together. As illustrated in FIG.5B, the outer covering component 505 is placed over the core component510. The outer covering component 505 may be aligned to the corecomponent 510 using one or more registration features 515. When theouter covering component 505 is placed over the core component 510, aninner surface of the outer covering component 505 and an outer surfaceof the core component directly contact at the supports of the patternedstructure (not shown), e.g., ridges of the patterned structure formedbetween the circumferential grooves 520. In some embodiments, the outercovering component 505 and core component 510 are fixed to each otherusing one or more glue layers (not shown).

FIG. 5C shows side and perspective views of the assembled core componentand outer covering component of FIG. 5B cut down to form the scleralcontact lens. After the outer covering component 505 has been mounted onthe core component 510, an outer surface of the outer covering component505 and the core component 510 are shaped to their desired form. In someembodiments, excess material of the outer covering component 505 andcore component 510 is cut away using a lathe, to form the core 530 andouter covering 535 of the contact lens. The core 530 and outer covering535 are shaped such that the outer surface of the outer covering alignswith an outer surface of the core, creating a smooth outer surface forthe contact lens. In addition, because the outer covering 535 issupported by the core 530 (e.g., via supports of the patternedstructure), the outer covering 535 can be shaped to a reduced thicknessto facilitate oxygen transmission from the local environment to theouter cavity formed by the recesses of the patterned structure betweenthe outer covering and the core.

FIG. 6A shows a side cross-section view of a core component and outercovering component assembled together, where a patterned structure isformed on the core component, in accordance with some embodiments. FIG.6A(1) shows a zoomed out cross-section of the core component and outercovering component, while FIG. 6A(2) shows a close-up view of theinterface between the core component and outer covering component zoomedin at area B shown in FIG. 6A(1). The core component 610 and outercovering component 605 illustrated in FIG. 6A may correspond to the corecomponent 510 and outer covering component 505 illustrated in FIGS. 5Aand 5B. As illustrated in FIG. 6A, the outer covering component 605 isplaced against the core component 610 such that an inner surface of theouter covering component 605 directly contacts the supports of apatterned structured 615 formed on a portion of an outer surface of thecore component 610. In other embodiments (not shown), the patternedstructure is formed on the outer covering component 605, which isaligned such that the supports of the patterned structure contact theouter surface of the core component 610.

The outer covering component and core component may contain extramaterial relative to their final desired forms, to facilitate handlingand/or alignment during assembly. For example, the outer coveringcomponent 605 may be formed from a thick material, allowing for it bemore easily handled and with less risk of deformation or breakage duringassembly. In addition, the core component 610 may comprise alignmentfeatures 620 that facilitate alignment between the outer coveringcomponent 605 and the core component 610.

In some embodiments, the outer covering component 605 and the corecomponent 610 are fixed to each other via a glue layer 625 deposited atan edge between the outer covering component 605 and the core component610. In some embodiments, the glue layer 625 may fill a space betweenthe outer covering component 605 and the core component 610 extending toan outer support of the patterned structure 615. However, the outersupport of the patterned structure, due to creating direct contactbetween the core component 610 and outer covering component 605,prevents the glue 625 from reaching the recesses within the patternedstructure 615. The glue 625 may function to seal the recesses of thepatterned structure 615 away from the outside environment. Consequently,air can only reach the cavity formed between the outer coveringcomponent 605 and core component 610 defined by the recesses through thegas permeable material of the outer covering component 605, thuspreventing outside debris and contaminants from entering the outercavity.

FIG. 6B shows a side cross-section view of the core component and outercovering component of FIG. 6A assembled together and cut down to formthe scleral contact lens. FIG. 6B(1) shows a zoomed out cross-section,while FIG. 6B(2) shows a close-up view of the interface between the corecomponent and outer covering component zoomed in at area C shown in FIG.6B(1). As illustrated in FIG. 6B, the assembled outer covering componentand core component are cut down to form a core 635 and outer covering630 having a smooth outer surface 640. The outer covering 630 is shapedto a thickness that allows for a desired amount of oxygen transmissionthrough the outer covering to reach the outer cavity of the contactlens. Because the patterned structure 615 is formed on the core 635 inthe embodiment illustrated in FIG. 6B, the outer covering 630 may beshaped to be of substantially uniform thickness. The outer covering 630is periodically supported by the supports of the patterned structure615, allowing for the thickness of the outer covering 630 to be reducedrelative to if the outer covering did not contact the core between theglue layers 625. For example, in some embodiments, the supports of thepatterned structure may be spaced such that the outer covering over thearea of the patterned structure does not span a distance of more than0.5 mm. As such, even though the contact points between the outercovering 630 and the supports of the patterned structure formed on thecore 635 may potentially decrease an area of the outer covering 630through which oxygen can be transmitted, the reduction in thickness thatis possible for the outer covering 630 may allow for the overall oxygentransmissibility of the outer covering to increase. In some embodiments,the supports of the patterned structure may be rounded or pointed, toreduce an area of the supports in direct contact with the outercovering.

FIG. 7 is a flowchart of a process for forming a scleral contact lens,in accordance with some embodiments. At 705, a core component is formed.The core component may correspond to the core component 505 illustratedin FIGS. 5A-5C or the core component 605 illustrated in FIGS. 6A and 6B.The core component may be formed to be thicker than the final desiredcore of the contact lens, and comprise one or more registration featuresfor aligning an outer covering, inner covering, one or more payloadcomponents, etc. In some embodiments, the core component is formed froma non-gas permeable material. For example, the material of the corecomponent may be selected to provide structural strength to the contactlens. At least a portion of an outer surface of the core component isshaped to receive a surface of an outer covering component.

At 710, an outer covering component is formed from an oxygen permeablematerial. The outer covering component comprises at least an innersurface shaped to be mounted on the core component. In some embodiments,the outer covering component is formed thicker in comparison to thefinal desired outer covering, to facilitate handling and assembly.

At 715, a patterned structure is formed on the core component or theouter covering component. The patterned structure comprises a pluralityof recesses interspersed between a plurality of supports. For example,in some embodiments, the patterned structure may comprise one or moreblind hole patterns formed on an inner surface of the outer coveringcomponent, wherein the blind holes correspond to the recesses andportions of the outer covering component between the blind holescomprise the supports. In some embodiments, portions of the outercovering component between the blind holes may be formed into one ormore pillars to function as supports. In some embodiments, the patternedstructure may comprise a plurality of circumferential grooves formed onan inner surface of the outer covering component or a portion of theouter surface of the core component, wherein the grooves correspond torecesses and ridges formed between pairs of adjacent grooves correspondto supports.

At 720, the outer covering component is attached to the core component.The outer covering component may be mounted to the core component suchthat the outer covering component and core component directly contacteach other at the supports of the patterned structure. In someembodiments, the outer covering component is attached to the corecomponent via a glue layer formed at the edge of the outer coveringcomponent. For example, the glue layer may be formed within a spacebetween the outer covering component and the core component extending toan outer support of the patterned structure, which prevents the gluefrom entering the recesses of the patterned structure. In someembodiments, an inner surface of the outer covering component is coveredwith a coating of hydrophilic material prior to the outer coveringcomponent being attached to the core component, to improve lubricity ofthe contact lens and/or to preserve gas permeability of the outercovering component.

At 725, the outer surface of the core component and outer coveringcomponent may be shaped to a final desired thickness of the contactlens. In some embodiments, the core component and outer coveringcomponent are cut down or lathed to form the final core and outercovering of the contact lens. In some embodiments, once the corecomponent and outer covering component are shaped to the desired formand thickness, a coating of hydrophilic material may be applied to theouter surface of the outer covering.

While the above description primarily discusses a patterned structureassociated with the interface between the outer covering and the core,similar techniques may be used to form a patterned structure associatedwith the interface between the inner covering and the core (e.g., apatterned structured formed on a portion of an inner surface of thecore, or an outer surface of the inner covering). This may allow theinner covering to be formed with reduced thicknesses in areascorresponding to the recesses of the patterned structure, which aresupported by the supports of the patterned structure.

In some embodiments, because the patterned structure can potentiallyaffect passage of light through the contact lens, the patternedstructure is only formed on portions of the contact lens that areoutside the central zone of the contact lens. In some embodiments, theouter covering may be disposed entirely outside the central zone of thecontact lens. As such, the patterned structured may be formed on theinner surface of the outer covering or on portions of the outer surfaceof the core to where the outer covering is to be mounted, withoutsubstantially affecting passage of light to the user's eye. On the otherhand, in embodiments where the inner covering is positioned to cover allor most of the wearer's cornea (e.g., to facilitate even distribution ofoxygen across the wearer's cornea through the inner covering), thepatterned structure may be formed only on portions of the inner coveringor core outside the central zone of the contact lens. It may not benecessary to form a patterned structure associated with the innercovering if a desired level of oxygenation can be achieved with an innercovering of substantially uniform thickness.

The foregoing description of the embodiments of the invention has beenpresented for the purpose of illustration; it is not intended to beexhaustive or to limit the invention to the precise forms disclosed, butmerely illustrates different examples. It should be appreciated that thescope of the disclosure includes other embodiments not discussed indetail above. Persons skilled in the relevant art can appreciate thatmany modifications and variations are possible in light of the abovedisclosure, without departing from the spirit and scope as defined inthe appended claims. Therefore, the scope of the invention should bedetermined by the appended claims and their legal equivalents.

Finally, the language used in the specification has been principallyselected for readability and instructional purposes, and it may not havebeen selected to delineate or circumscribe the inventive subject matter.It is therefore intended that the scope of the invention be limited notby this detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsof the invention is intended to be illustrative, but not limiting, ofthe scope of the invention, which is set forth in the following claims.

What is claimed is:
 1. A scleral contact lens that mounts to a sclera ofan eye, comprising: a core having an outer surface that faces outwardsaway from the eye; and a gas-permeable covering having an inner surfacethat covers at least a portion of the outer surface of the core, thecovering's inner surface and the core's outer surface forming aninterstitial cavity therebetween that receives oxygen from the externalenvironment through the gas-permeable covering; wherein at least one ofthe core's outer surface and the covering's inner surface comprises apatterned structure, the patterned structure has a plurality of recessesinterspersed with a plurality of supports, the core and covering contacteach other at the supports, and the recesses form the interstitialcavity.
 2. The scleral contact lens of claim 1, wherein the covering'sinner surface comprises the patterned structure.
 3. The scleral contactlens of claim 2, wherein, within the patterned structure, the coveringhas a thickness of not more than 100 um over at least ⅓ of an overallarea of the patterned structure.
 4. The scleral contact lens of claim 1,wherein the core's outer surface comprises the patterned structure. 5.The scleral contact lens of claim 4, wherein, for a region of thecovering facing the patterned structure, the covering has an averagethickness of not more than 100 um.
 6. The scleral contact lens of claim1, wherein the patterned structure comprises a pattern of blind holes.7. The scleral contact lens of claim 6, wherein the pattern of blindholes comprises: a first plurality of non-overlapping blind holes, eachhaving a first depth and a first radius; and a second plurality of blindholes overlaying the first plurality of blind holes, each having asecond depth shallower than the first depth and a second radius largerthan the first radius, wherein the second plurality of blind holesoverlap with each other to form a plurality of columns between the firstplurality of blind holes.
 8. The scleral contact lens of claim 6,wherein the blind holes are arranged in a hexagonal pattern.
 9. Thescleral contact lens of claim 6, wherein the blind holes are frustums.10. The scleral contact lens of claim 1, wherein the patterned structurecomprises a plurality of grooves.
 11. The scleral contact lens of claim1, wherein the patterned structure comprises a plurality of concentricgrooves.
 12. The scleral contact lens of claim 1, wherein the patternedstructured covers an area of not more than 100 mm².
 13. The scleralcontact lens of claim 1, wherein a distance to a nearest support doesnot exceed 0.5 mm for any point in the interstitial cavity.
 14. Thescleral contact lens of claim 1, wherein the covering has an annularshape with an area of not more than 100 mm².
 15. The scleral contactlens of claim 1, wherein the covering has an annular shape with a widthof not more than 3 mm.
 16. The scleral contact lens of claim 1, whereinthe core has an inner surface that faces inwards towards a cornea of theeye, and the scleral contact lens further comprises: a gas-permeableinner covering under the core's inner surface and disposed over thecornea of the eye, the inner covering and the core's inner surfaceforming a second interstitial cavity therebetween that passes oxygen tothe cornea of the eye through the gas-permeable inner covering; whereinthe core has air paths for flow of oxygen through the core between thetwo interstitial cavities.
 17. The scleral contact lens of claim 1,wherein the core carries an electronic payload.
 18. The scleral contactlens of claim 17, wherein the electronic payload comprises afemtoprojector that projects images onto a retina of the eye.
 19. Thescleral contact lens of claim 17, wherein an outer surface of thecovering and the inner surface of the covering are coated with ahydrophilic material configured to preserve gas-permeability of thecovering.
 20. The scleral contact lens of claim 1, wherein a portion ofthe core not covered by the covering is coated with a hydrophilicmaterial.
 21. A contact lens mountable on an eye, the lens comprising: acore having an outer surface that faces outwards, away from the eye, andan inner surface that faces inwards, towards the eye; a gas-permeableouter covering having an inner surface that covers at least a portion ofthe outer surface of the core, the outer covering's inner surface andthe core's outer surface forming a first interstitial cavitytherebetween that receives oxygen from surrounding air through thegas-permeable outer covering; a gas permeable inner covering that coversat least a portion of the core's inner surface, the inner covering andthe core's inner surface forming a second interstitial cavitytherebetween that passes oxygen to the eye through the gas-permeableinner covering; and at least one air path through the core that permitsoxygen to flow between the first and second interstitial cavities;wherein at least one of the core's outer surface and the outercovering's inner surface comprises a plurality of recesses interspersedwith a plurality of supports, the core and the outer covering contactingeach other at the supports, and the recesses forming the firstinterstitial cavity.
 22. The contact lens of claim 21, wherein the corecarries a payload.
 23. The contact lens of claim 22, wherein the payloadcomprises a femtoprojector.